Process for hydrogenating acrylonitrile to propionitrile

ABSTRACT

The hydrogenation of acrylonitrile to propionitrile is disclosed using a catalyst having a complex of (A) nickel, and (B) an organometallic reducing agent on (C) an acidic, silica-based support material. The complex has a molar ratio of (B) to (A) of about 2:1 to 50:1 or more, preferably about 3:1 to 20:1, and with (A) being a minor catalytic amount, e.g. from about 0.1 to 5 weight percent, based on the support. Preferred catalyst components include nickel acetylacetonate and diisobutylaluminum hydride on a solid, acidic silica-based support.

United States Patent You [451 June 20, 1972 [54] PROCESS FORHYDROGENATING ACRYLONITRILE TO PROPIONITRILE [72] inventor: Jin Sun You,South Holland, 111.

[73] Assignee: Atlantic Rlchfield Company, New York,

[22] Filed: Jan. 16, 1970 21 Appl. No.: 3,519

3,453,314 7/1969 Smeykal etal ..260/465.l

Primary Examiner-J. P. Brust Attorney-John W. Behringer, Eugene L.Bernard, Martin J. Brown, James N. Dresser, W. Brown Morton, Jr., JohnT. Roberts, Malcolm L. Sutherland and Morton, Bernard, Brown, Roberts &Sutherland [57] ABSTRACT The hydrogenation of acrylonitrile topropionitrile is disclosed using a catalyst having a complex of (A)nickel, and (B) an organometallic reducing agent on (C) an acidic,silica-based support material. The complex has a molar ratio of (B) to(A) of about 2:1 to 50:l or more, preferably about 3:1 to 20: l, andwith (A) being a minor catalytic amount, e.g. from about 0.1 to 5 weightpercent, based on the support. Preferred catalyst components includenickel acetylacetonate and diisobutylaluminum hydride on a solid, acidicsilica-based support.

10 Claims, No Drawings PROCESS FOR HYDROGENATING ACRYLONITRILE TOPROPIONITRILE This invention relates to the hydrogenation ofacrylonitrile. In particular, this invention relates to a process forthe hydrogenation of acrylonitrile to propionitrile in the presence of aparticular catalyst.

The binary, homogeneous catalyst system of a nickel source and anorganometallic reducing agent is known to be an effective catalyst forthe hydrogenation of olefins. However, with acrylonitrile as the feed,the catalyst promoted polymerization selectively to polyacrylonitrilewithout the acrylonitrile being hydrogenated.

It has now been found that complexes of nickel with an organometallicreducing agent capable of reducing nickel acetylacetonate to anoxidation state of less than 2, on a solid, acidic silica-based supportprovide a catalyst composition having highly desirable physical andchemical characteristics, and particularly, excellent catalyst activityand selectivity for the hydrogenation of acrylonitrile to propionitrile,in the presence or absence of an inert solvent. The catalyst complex hasa molar ratio of reducing agent to nickel of about 2:1 to 50:] or more,preferably about 3:1 to 20:l. The nickel and reducing agent are providedin a minor amount effective to catalyze the hydrogenation reaction. Thenickel can be present, for example, in an amount of from about :1 to 5weight percent of the base, preferably from about 0.1 to 1 weightpercent of the base.

In the preparation of the catalyst composition used in the process ofthe present invention, the nickel source is provided by compounds of themetal which are at least slightly soluble in some solvent wherein thenickel-reducing agent complex can be formed. Suitable sources of thenickel can include, for example, halides, e.g. NiCl NiBr Nildihydrocarbyloxy nickel, i.e., Ni(OR) where R represents alkyl, aryl,aralkyl, and the like groups; dihydrocarbyloxy nickel carboxylate, i.e.,(RO) NiOOCRwhere R and R are as defined above as R; diphosphinecomplexes, e.g. Ni[(C I-I PC H P(C H ]X where X is a halide. Alsoavailable as nickel sources are chelates formed by the nickel and weakfield ligands, such as B- diketones of B-keto-carboxylic acid esters andsalts of carboxylic acids. Examples of these types of nickel sourcesinclude [3- diketonato nickel (II), acetylacetonato nickel (II),propylacetonato nickel (II), benzoylacetonato nickel; chelates fromB-ketocarboxylic acid esters; salts of saturated monocarboxylic acids,e.g. nickel for-mate, nickel propionate, nickel caproate, nickeloctoate, nickel palmitate, nickel stearate, and the like; salts ofcorresponding unsaturated monocarboxylic acids, e.g. nickel acrylate,nickel vinyl acetate, and the like; salts of saturated dicarboxylicacids, e.g. nickel adipate, nickel decane-l,IO-dicarboxylate, and thelike; salts of corresponding unsaturated dicarboxylic acids, e.g.,nickel muconate and the like; salts of cyclic and aromatic carboxylicacids, e.g.,

nickel cyclohexane carboxylate, nickel benzoate, nickel phthalates,nickel phenylacetate and the like; and dialkoxycarboxylates, e.g. nickeldimethoxyacetate and the like. Preferred as a source of nickel is nickelacetylacetonate.

As examples of reducing agents in this catalyst, there may be mentionedthe non-halogen containing organometallic and organometallic hydridecompounds which correspond to the general fonnulas:

wherein M is a metallic element of coordination number n, H is hydrogen,R is hydrocarbyl, e.g. alkyl or aryl, of two to about carbon atoms and yis a number having a value from O to n; preferably y is at least 1 lessthan n so that R is at least 1. Preferred metallic elements in the abovecompound include aluminum, magnesium, beryllium, lead, zinc, and tin.Aluminum is preferred. Examples of suitable compounds are triisobutylaluminum, di-isobutyl aluminum hydride, triethylaluminum,tripropylaluminum, diethyl aluminum hydride, the corresponding compoundsof the other metals designated by M, etc. The reducing agent must becapable of reducing nickel acetylacetonate, preferably to an oxidationstate lower than 2 and even to 0.

A solid support suitable for use in the catalyst of the presentinvention is an acidic, silica-based material e.g. having a D L activityof at least about 20, preferably at least about 30 when determinedaccording to the method of Birkhimer et al., A Bench Scale Test Methodfor Evaluating Cracking Catalysts," Proceedings of the AmericanPetroleum Institute, Division of Refining, Vol. 27(Ill), page (I947) andhereinafter referred to as Cat A. The silica-based support preferablyhas a substantial surface area as determined by the BET nitrogenabsorption procedure (JACS, Vol. 60, pp. 309 et seq. (1938). The surfacearea of the support can be at least about 50 square meters per gram, andsuch surface areas are often up to about 500 or more m lgm, preferablyabout to 400 m /gm. It is preferred that the catalyst support berelatively dry to avoid undue reaction with and loss of catalyticpromoting materials. Thus, it is advantageous that the support becalcined, e.g. at temperatures of about 600 to 1,500F., or more, toreduce the water content, but such calcination should not be so severethat the support is no longer catalytically-active.

The support component can contain other materials in addition to silicawhich materials, when combined with silica, provide an acidic materialas in, for instance, the case of silicaalumina. Often these materialsare one or more oxides of the metals of groups II, III and IV of theperiodic table. Examples of the composites contemplated herein under thegeneric designation of silica-based materials are often composedpredominantly of or even to a major extent of silica. These supportsinclude, for example, silica-alumina, silica-boria, silica-zirconia,silica-magnesia, silica-alumina-zirconia, silicaalumina-thoria,silica-alumina-magnesia, and the like. The silica-based support cancontain amorphous or crystalline material such as a crystallinealuminosilicate, for instance, having pore openings with diameters inthe 6 to 15 angstrom unit range. The support often contains silica andalumina and such supports, whether naturally-occurring as inacid-treated clays, or a synthetic gel, will frequently contain about 10to 60, preferably about 15 to 45, weight percent alumina. In addition,such silicaalumina supports can, and preferably do, contain a portion ofthe alumina as a separate, distinct phase.

A highly preferred catalyst support can be made by combining asilica-alumina hydrogel with a hydrous alumina with or without(preferably without) a crystalline aluminosilicate. An advantageoushydrous alumina component is, when analyzed by X-ray diffraction of drysamples, either one or a mixture of amorphous hydrous alumina and amonohydrate, e.g., boehmite, of less than about 50 A, preferably lessthan about 40 A, crystallite size as determined by half-widthmeasurements of the (0, 4, 1) X-ray diffraction line calculated by theDebye-Scherrer equation. The mixture of the catalyst precursorcomponents can be dried, e.g., at about 220 to 500F., to convert thesilica-alumina hydrogel to xerogel form. The dried material can then becalcined, e.g., at a temperature of about 700 to 1,500F., preferablyabout 800 to 1,400F., to provide the active catalyst support. Duringcalcination, the separate hydrous alumina phase of the mixture isconverted to a gamma form or other catalytically-active alumina.

In providing the preferred catalyst support precursor for drying, thecomponents can be combined in any suitable manner or order desired, andadvantageously each of the components is in the mixture infinely-divided form, preferably the particles are principally less thanabout 300 mesh in size. The finely-divided material can have an averageparticle size of about 10 to 150 microns and can be used to make acatalyst of this particle size which can be employed in a fluidized bedtype of operation. However, if desired, the mixture of catalyst supportcomponents can be placed in macrosized form, that is, made intoparticles as by tabletting, extruding, etc., to sizes of the order ofabout 1/64 to A in. or more in diameter and about l/32 to l in. or morein length, before or after drying or calcination. If formation of themacrosized particles is sub sequent to calcination and the calcinedparticles have been contacted with water, the material can berecalcined.

On a dry basis, the preferred supports of the catalysts of the presentinvention contain about 45 to 95 weight percent of the amorphoussilica-alumina xerogel, about 5 to 55 weight percent of the separatelyadded alumina phase, and about to 50 weight percent of the crystallinealuminosilicate, preferably the proportions of these ingredients areabout 75 to 90 percent, about ID to 25 percent and about 0 to 20percent, respectively. If present, the crystalline aluminosilicate isusually at least about 1 weight percent, preferably at least about 5weight percent, based on the dried support. The alumina content from thesilica-alumina xerogel and the separate alumina phase is about 20 to 70weight percent, preferably about 25 to 60- weight percent, based on thedried support.

Also, the catalyst support generally contains less than about 1.5 weightpercent, preferably less than about 0.5 weight percent, sodium.

The silica-alumina component of the precursor of the preferred catalystsupport of the present invention can be silica-alumina hydrogel whichcontains about 55 to 90, preferably 65 to 75, weight percent silica andabout to 45, preferably about 25 to 35, weight percent alumina, on a drybasis. The silica-alumina can be naturally-occurring or can besynthetically prepared by any desired method and several procedures areknown in the art. For instance, an amorphous silica-alumina hydrogel canbe prepared by co-precipitation or sequential precipitation by eithercomponent being the initial material with at least the principal part ofthe silica or alumina being made in the presence of the other.Generally, the alumina is precipitated in the presence of a silica gel.it is preferred that the silica-alumina hydrogel be made by forming asilica hydrogel by precipitation from an alkali metal silicate solutionand an acid such as sulfuric acid. Then alum solution may be added tothe silica hydrogel slurry. The alumina is then precipitated by raisingthe pH into the alkaline range by the addition of an aqueous sodiumaluminate solution or by the addition of a base such as ammoniumhydroxide. Other techniques for preparing the silica-alumina hydrogenare well known in the art, and these techniques may be used in thepractice of the invention.

The alumina hydrogel which can be combined with the silica-alumina ismade separately from the silica-alumina. The alumina hydrogel may beprepared, for example, by precipitation of alumina at alkaline pH bymixing alum with sodium aluminate in an aqueous solution or with a basesuch as soda ash, ammonia, etc. As noted above, the alumina hydrogel canbe in the form of amorphous hydrous alumina or alumina monohydrate,e.g., of up to about 50 A crystallite size as determined by X-raydiffraction analysis. The amorphous hydrous alumina generally containsas much combined water as does an alumina monohydrate. Mixtures of themonohydrate and amorphous forms of hydrous alumina are preferred andoften, this phase is composed of at least about 25 percent of each ofthe separate members.

In preparing the catalyst support, one may separately filter thesilica-alumina hydrogel and the hydrous alumina and intimately mix thesematerials, for instance, by colloidal milling. Although in thisparticular procedure a low sodium crystalline aluminosilicate can beadded after the milling, this ingredient can also be combined before thecolloidal milling operation. The mixture is dried, water washed toacceptable concentrations of, for instance, sodium, and redried in thepreferred procedure. The drying, especially the initial drying, isadvantageously effected by spray drying to give microspheres.

The crystalline aluminosilicate which can be present in catalyst supportof the present invention, can have pore openings of 6 to A, in diameterand preferably the pore openings have a diameter of 10 to l4 A. Usually,with a given material, the pores are relatively uniform in size andoften the crystalline aluminosilicate particles are primarily less thanabout 15 microns in size, preferably less than about 10 microns. In thecrystalline aluminosilicate the silica-to-alumina mole ratio is oftengreater than about 2:1 and is usually not above about 12:1, preferablybeing about 4 to 6:]. The

aluminosilicate may be available in the sodium form, and thesodium canbe removed before or after the crystalline aluminosilicate is added tothe other catalyst support ingredients.

It is preferred to exchange the sodium with ammonium ions, for instance,through contact with an aqueous solution of ammonium chloride or anotherwater-soluble ammonium compound. Subsequently, during drying and/orcalcination, the ammonium ion may break down to release ammonia andleave an acid site on the aluminosilicate. On a molar basis, theammonium or hydrogen ion is usually at least about 10 percent or even atleast about 50 percent, based on the alumina content of the crystallinealuminosilicate. Suitable replacements for the sodium also include thepolyvalent metals of the periodic chart, including the group lI-a andrare earth metals such as cerium, etc. The metals may be present alongwith the ammonium or hydrogen cations.

The order in which components are combined to prepare the supportedcatalyst used in the present invention can be varied. The catalysts canbe conveniently prepared by impregnating the silica-based supportmaterial with a solution of the nickel component, e.g., nickelacetylacetonate, in a solvent, e.g., methanol, forminglight-green-colored pellets. The nickelimpregnated support after solventremoval is then contacted with a solution of the reducing agentcomponent forming a black-colored catalyst system.

Although the foregoing is a preferred method for preparing the catalystused in the process of this invention, the nickel complex can first beprepared for subsequent impregnation into the silica-based support. Thepreparation of the unsupported nickel complex can be conducted byforming the complex of the nickel source and then adding to a solutionor suspension, of that complex, in a suitable organic solvent, thereducing agent. Suitable organic solvents are those which are inert tothe catalyst and which will not enter into, or deleteriously affect, theeventual hydrogenation reaction. As specific examples thereof may bementioned aromatic and aliphatic hydrocarbons and their halogenated,e.g., chlorinated, derivatives. Oxygen-containing solvents are generallyto be avoided for this purpose.

Thus, for example, one method of preparing the nickel complex caninvolve stirring, preferably at room temperature, a mixture of nickelacetylacetonate and toluene. The reducing agent can be added directly.The addition to the solution of the reducing agent is preferablyconducted in a dry-inert atmosphere, out of the presence of air oroxygen, for instance, in an autoclave. Within a relatively short periodof time after the admixing of the components, e.g., about 5 to 15minutes, the catalyst composition is formed, preferably as a colloidalprecipitate suitable for impregnating the silica-based supports of thisinvention.

The catalyst composition, as described, may be used to catalyze thehydrogenation of acrylonitrile to propionitrile, in the presence orabsence of an inert solvent, such as toluene or other hydrocarbonliquid. Hydrogenation can be affected by contacting the acrylonitrile inthe presence of a catalyticallyeffective amount of the catalyst at atemperature of from about 75 to 250F., preferably to 200F., and in thepresence of molecular hydrogen in an amount sufficient for thehydrogenation of acrylonitrile to propionitrile. The hydrogen can bepresent at a pressure of from about 50 to 2,000 or more psig.,preferably 250 to 1,500 psig. Generally, the higher the temperature, thelower the pressure that'can be used. The amount of catalyst present canoften be from about 0.5 to 100 weight percent, preferably 5 to 50 weightpercent of catalyst composition based on the weight of the acrylonitrilefeed. The catalyst system can also be utilized in a continuous reactorfor the continuous hydrogenation of acrylonitrile.

The preparation of an acidic silica-alumina support is illustrated byexamples I-IIl, and the support contains a separate phase of alumina.

EXAMPLE I An alumina hydrogel is prepared as follows:

In a tank containing 5,700 gallons of water at 85F are dissolved 300lbs. of soda ash. When the soda ash has been dissolved, 180 gallons of a39 percent concentration aqueous sodium aluminate solution are pumpedinto the tank in about a 15-minute period. The contents of the tank areat about 84F. Six-hundred gallons of aqueous aluminum sulfate of 7.8percent concentration, as A1 are added to the admixture over an80-minute period with water of dilution in conjunction with, and inaddition thereto, diluting the reaction mass at a rate of 25 gallons perminute.

The pH of the resulting aqueous reaction mass is adjusted to 8.0 withabout 75 gallons of 39 percent concentration aqueous sodium aluminatesolution which, while being added, is also diluted continuously withwater at a rate of 35 gallons per minute over a 7% minute additionperiod. The contents of the tank are heated to about 100F., and pumpedto storage.

The precipitated, hydrated alumina is thereafter filtered on a large gelfilter. The filtered product is partially purified by a one-cycle,water-wash on the filter on which it is collected. This filter is astring vacuum type drum filter with a built-in water spray nozzledirected toward the filter drum. Material on the drum is contacted withwater as the drum rotates past the nozzle. After washing, the wetalumina hydrogel is stripped from the drum. This hydrogel analyzes about50 percent boehmite having a crystallite size of about 35 A, and 50percent amorphous hydrous alumina as detemiined by X-ray diffraction ondried samples.

EXAMPLE 11 A silica-alumina hydrogel is prepared by the followingtechnique:

To a batch tank is added 4,275 gallons of water preheated to 90F, and865 gallons of sodium silicate solution (28.8 weight percent SiO 4041.5Baume at 68F., and Na ozSiO ratio of 113.2) is added. The batch isstirred for minutes. The concentration of the sodium silicate, as SiO inthe batch is 6.3 weight percent.

With the batch at 90F., 302 gallons of 34.5 weight percent sulfuric acidsolutionat 182F. are added over a period of 45 minutes. The gel formsabout 35 minutes after acid addition is begun. The pH is adjusted to8.0-8.5. The batch is agitated for 10 minutes.

Then 715 gallons of alum (7.8 weight percent, as A1 0 is added to thegel over a period of about 36 minutes. The batch is agitated for anadditional 5 minutes whereupon 205 gallons of sodium aluminate solution(24.4 weight percent as A1 0 diluted in 1,080 gallons of water is addedover a period of 17 minutes. After all the sodium aluminate is added,the pH is checked. It should be between 5.0 and 5.2. The alumina contentof the silica-alumina hydrogel is 30-31 percent.

EXAMPLE Ill The silica-alumina hydrogel product of example 11 and 1740gallons of the alumina hydrogel filter cake of example 1 are mixedtogether for 1 hour. The finished batch has a pH of 5.5 to 5.6 and atemperature of about 110F. The aqueous gel mixture is then pumped to adewatering filter, and the filter cake from said dewatering filter and aportion of aqueous gel are blended to give a gel slurry of about 14weight percent solids. A portion of this hydrogel mixture was slurried,as a thick flowable paste, with a Lightnin stirrer fitted with acage-beater and a propellor, for about 10 minutes to give a thoroughdispersion. The product was stirred 1 minute at 14,500 rpm., in a WaringBlender and dried in a laboratory spray-drier. The spray-dried materialwas washed with water to acceptable impurity levels and dried at 230F.The washed and dried material analyzed 0.08 percent S0 and less than 25ppm Na O. The dried material as such was used as the catalyst support,as were extruded forms thereof and tablets (pellets) having diameters ofabout A; inch and lengths of about It: to 9% inch. Before use, thecatalyst support was calcined in a mufile furnace by raising thetemperature by 300F. per hour until 1,350F. was reached. Thistemperature was then held for 3 hours. The calcined particles had asurface area of about 320 to 340 square meters per gram.

The preparation and utilization of the catalyst of the present inventionare illustrated by the following examples. Details of reactionconditions, catalyst compositions, and product distribution for theseexamples are listed in tables I and [1.

EXAMPLE IV A 300 cc stainless steel autoclave equipped with a magneticstirrer was used as a reactor. The black solid catalyst system preparedfrom both 1.2 m moles nickel acetylacetonate and 14.5 m molesdiisobutylaluminum hydride were charged to the reactor along with 40 ml.toluene and 4.0 g pellets (V8 in. diameter /4-1/ 16 in. length) of thesolid, acidic support prepared in example 111 These components wereallowed to react under psig. hydrogen and at 100160F. for 15 minutes. Aslight excess of nickel not supported on the base was present. As soonas acrylonitrile (60 ml.) was introduced into the system, the system waspressured with hydrogen to 1,400 psig., and hydrogen uptake wasmeasured. The initial pressure of the system (1,400 psig.) dropped to600 psig. within 45 minutes, and then to 350 psig. after another 60-minute period. The black reaction mixture was discharged from thereactor, and was treated with dilute HCl to isolate an organic liquidportion and some polymer product from an aqueous layer. The organicliquid was again separated from the polymer product, and analyzed bymass spectroscopic and proton NMR techniques. The polymeric product,which dissolved only in dimethylsulfoxide, was precipitated by additionof a large excess of methanol. After this precipitated product waswashed with pentane and ether, it was dried and identified by infraredspectroscopic study. Details of the results are listed in table 1 andII. About 74 mole percent of acrylonitrile was hydrogenated topropionitrile, and a very small portion of the acrylonitrile wasconverted to polymeric product.

EXAMPLE V The previous run was repeated under similar conditions exceptthat the system now described did not have the solid, acidicsilica-based support pellets present as one of the catalyst components.After 40 ml of acrylonitrile was added to the black heterogeneous systemcontaining 1.1 m moles nickel acetylacetonate, and 15.4 m molesdiisobutyl aluminum hydride in 50 ml toluene, hydrogen was introduced toattain 1,200 psig. hydrogen pressure. No significant hydrogen uptake wasobserved for a 100 minute period. A dark-red reaction mixture wasremoved from the reactor, and the polymeric product was isolated andpurified as previously described. The infra-red spectrum of this productproved to be identical with the known polyacrylonitrile product. In thecatalyst system without the solid, acidic silica-based supportcomponent, acrylonitrile undergoes polymerization under a hydrogenatmosphere instead of being hydrogenated. Thus, judging from the resultsobtained from this and previous example, the solid, acidic silica-basedsupport is an essential catalytic component for the hydrogenation.Furthermore, it is obvious that the nature of the catalytic speciesformed in the binary system containing nickel acetylacetonate anddiisobutylaluminum hydride in toluene can be substantially changed withthe solid, acidic silica-based support as an essential component forhydrogenation it also serves as an effective supporting base as well.

EXAMPLE V1 The black catalyst, prepared from 1.1 m moles nickelacetylacetonate and diisobutylaluminum hydride (14.5 m moles), wassupported on 4.0 g pellets of the solid, acidic support prepared inexample 111. The resulting black supported catalyst was aged for aboutthree hours by running the hydrogenation reaction with variousunsaturated compounds such as heptene-3, cyclohexene, and1,5-cyclooctadiene, in four consecutive runs before an acrylonitrilesubstrate was fed to the catalyst. A slight excess of nickel notsupported on the base was present.

Acrylonitrile (40 ml) was injected to the aged catalyst, and the reactorwas pressured with hydrogen to 1,200 psig. Hydrogen-uptake from 1,200 to410 psig. reactor pressure was noticed over a 170 minute period. In thisrun, 87 mole percent of the acrylonitrile substrate was hydrogenated topropionitrile, and the polymeric product was obtained to only a veryminor extent. This clearly demonstrates that'the supported catalyst canbe successfully used for hydrogenation of acrylonitrile in the absenceof an inert solvent. 1t is natural to expect that the virgin supportedcatalyst will show'a higher catalytic activity for hydrogenation ofacrylonitrile to propionitrile than the aged catalyst used in thepresent run.

EXAMPLE V11 The black supported catalyst, prepared from 1.1 m molesnickel acetylacetonate, 15.8 m' moles diisobutyl aluminum hydride and4.0 g of the solid, acidic support prepared in example 111 was aged for2% hours through two consecutive hydrogenations using first4-vinyl-1-cyclohexene and then styrene as the feed. A slight excess ofnickel not supported on the base was present. To the resulting agedcatalyst, 50 ml acrylonitn'le was introduced and the pressure of thesystem raised to 1,100 psig. with hydrogen. A moderate hydrogen uptakefrom 1,100 to 500 psig. was observed within 120 minutes. About 49 molepercent of acrylonitrile was converted to propionitrile. No appreciablepolymeric material was present in the product.

TAB LE I which comprises conducting said hydrogenation in contact withthe catalyst which consists essentially of a complex of A. nickel, and yB. a reducing agent capable of reducing nickel acetylacetonate to anoxidation state of less than 2 having the formula R' o MH wherein M isan element selected from the group consisting of 10 aluminum, magnesium,beryllium, lead, zinc, and tin having a coordination number n R ishydrocarbyl of two to about carbon atoms selected rom the groupconsisting of alkyl and aryl, and y is 0 to n, with the proviso thatthere must be present at least one R group, on a solid, acidicsilica-based support, 15 the molar ratio of B to A in the complex beingabout 2:1 to 50:1 and with (A) being a minor, catalytic amount based onthe support.

2. The process of claim 1 wherein the hydrogenation is perfonned at atemperature of from about 75 to 25()F., and a pressure of from about 100to 2,000 psig.

3. The process of claim 2 wherein the hydrogenation is performed at atemperature of from about 100 to 200F., and a pressure of from about 250to 1,500 psig.

4. The process of claim 1 wherein (B) is an organoaluminum hydride.

5. The process of claim 1 wherein the molar ratio of B to A is about 3:1to 20:1 and (A) is from about 0.1 to 1 weight percent of the totalcatalyst.

6. The process of claim 5 wherein the nickel is provided as nickelacetylacetonate.

Catalyst composition Reaction condition Diisobutyl Nickel aluminumlelletized Hour 'Iempera- Reaction Example :icetylaceliydiide, supportToluaged, Pressure, ture, time, number tomato, mm. mm. grains, g. eno,mm. 111'. p.s.1.g. F. inins.

TABLE I1 7. The process of claim 6 wherein (B) is an organoaluminumhydride. I H Analysis of product 8. The process of claim 1 wherein thesupport 18 silica-alu- Unreactfd P mina calcined at a temperature offrom about 700 to 1,500F. Acrylo- 9. The process of claim 8 wherein thesupport 15 comprised Example mile "1016 mole of about 45 to 95 weightpercent amorphous silica-alumma, number feed, 1111. percent percent 1.olymcric product and about 5 to weight percent alumina, the total alumma5 small amountcontent of said support being about 20 to 70 weightpercent. 40 Polymer only. 40 12.0 87.1 Very small amount. 70 50 491None- 10. The process of claim 9 wherein sa1d alumina results from thecalcination of a member selected from the group It is claimed: 55consisting of amorphous hydrous alumina, alumina 1. In a process forhydrogenating acrylonitrile to propionitrile in the presence ofhydrogen, the improvement monohydrate and mixtures thereof.

2. The process of claim 1 wherein the hydrogenation is performed at atemperature of from about 75* to 250*F., and a pressure of from about100 to 2,000 psig.
 3. The process of claim 2 wherein the hydrogenationis performed at a temperature of from about 100* to 200*F., and apressure of from about 250 to 1,500 psig.
 4. The process of claim 1wherein (B) is an organoaluminum hydride.
 5. The process of claim 1wherein the molar ratio of B to A is about 3:1 to 20:1 and (A) is fromabout 0.1 to 1 weight percent of the total catalyst.
 6. The process ofclaim 5 wherein the nickel is provided as nickel acetylacetonate.
 7. Theprocess of claim 6 wherein (B) is an organoaluminum hydride.
 8. Theprocess of claim 1 wherein the support is silica-alumina calcined at atemperature of from about 700* to 1,500*F.
 9. The process of claim 8wherein the support is comprised of about 45 to 95 weight percentamorphous silica-alumina, and about 5 to 55 weight percent alumina, thetotal alumina content of said support being about 20 to 70 weightpercent. 70
 10. The process of claim 9 wherein said alumina results fromthe calcination of a member selected from the group consisting ofamorphous hydrous alumina, alumina monohydrate and mixtures thereof.